The pair’s new venture company, Atomico Ventures, dubs itself as a firm “investing in disruption.” Zennström and Friiss are already credited with helping to launch companies including Internet voice-communications pioneer Skype and digital file-sharing company Kazaa.

The new Rdio service, to be launched in the United States, will reportedly allow users to share and archive music via a Web browser and stream in on mobile devices. Pricing information is not yet available, though the pair is reportedly looking into deals with leading music labels.

If executed correctly, the service could present a formidable challenge to Internet subscription music kings Napster and Pandora (News - Alert) – especially if it executes a solid mobile strategy. Pandora’s co-founder and Chief Strategy Officer Tim Westergren recently told TMCnet it is expanding its mobile presence as we speak. Today, as many as 30 percent of Pandora listening is already on mobile, and the company is adding more than half of its new users on mobile devices.

“We’re the number three downloaded iPhone (News - Alert) app in the world with over 8 million downloads - and we are adding almost 30,000 new iPhone listeners every day,” Westergren told TMCnet.

Neither Zennström nor Friis could be reached for comment.

Marisa Torrieri is a TMCnet Editor. To read more of her articles, please visit her columnist page.